1. Field of the Invention
This invention relates to a radio wave generating device mounted on various artificial satellites including satellite-broadcasting artificial satellites (which are hereinafter referred to as broadcasting satellites), and more particularly to a communication subsystem for artificial satellites for transmitting, for example, broadcasting waves to specified service areas from space.
2. Description of the Related Art
As is well known in the art, the Japanese broadcasting satellite is controlled to station on a geostationary orbit above the equator at the 110th degree of east longitude according to the international agreement. The broadcasting satellite includes a communication subsystem for artificial satellites for receiving satellite broadcasting waves generated from earth broadcasting stations and transmitting the received wave to the service areas (mainly in Japan). The transmitting/receiving antenna of the communication subsystem is set on the broadcasting satellite to a direction of the service areas seeing from the geostationary orbit above 110th degree of east longitude.
The construction of the satellite is disclosed in, for example, the paper "PROCEEDINGS OF THE THIRTEENTH INTERNATIONAL SYMPOSIUM ON TECHNOLOGY AND SCIENCE" made public in the symposium held in Tokyo Japan, in 1982. "BS-2 SPACE CRAFT DESIGN" is disclosed in the 14th chapter (1421 to 1425) of this paper.
In a system using such a broadcasting satellite, it is sometimes necessary to replace the satellite which was previously launched and placed in orbit, by a new satellite. In this case, if the new satellite is placed in orbit and set into test operation while the old satellite is kept under operation, interference occurs between waves transmitted from the communication subsystems of the old and new satellites. In order to prevent such an interference, the new satellite is first set in a provisional orbit position which is sufficiently separated away from the old satellite and cannot been covered by the beam of the receiving antenna of the ground. Then, the operation test for instruments mounted on the new satellite including the communication subsystem is effected according to commands from the earth station.
In a case where the new satellite is set in the provisional orbit and the operation test for the onboard instruments is effected as described above, it is necessary to move the new satellite into the preset orbit after the completion of the operation test. Conventionally, it takes two weeks to one month for the new satellite to move from the provisional orbit to the preset orbit.
According to the method of replacing the broadcasting satellites, it becomes impossible to effect the sufficient test operation when rapid replacement of the satellites is required. Further, when the operation test for the new satellite is effected, it is better to set the new satellite into the running-in condition at the final orbit position and then effect the operation test. This is because the running-in condition is much similar to the actual operation condition, and a more precise test result can be obtained.